#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<string.h>
int main()
{
    int arr[200];
    memset(arr, 0, sizeof(int) * 200);
    char ch[1000000];
    scanf("%s", ch);
    int n = strlen(ch);
    for (int i = 0; i < n; i++)
    {
        arr[ch[i]]++;
    }
    int count = 0;
    for (int i = 0; i < 200; i++)
    {
        if (arr[i] != 0)
        {
            count++;
        }
    }
    printf("%d", count);
    return 0;
}